The present invention relates to a method for segmenting a plate-like material, particularly a method of segmenting a semiconductor wafer having a plurality of regularly arranged elements thereon into pellets including the individual elements.
In the manufacture of semiconductor devices, there are generally involved the steps of forming a plurality of regularly arranged elements in one main surface of the semiconductor wafer by performing diffusion, evaporation and other treatments on the surface, and then segmenting the semiconductor wafer into pellets including the respective elements.
For the purpose of segmenting the semiconductor wafer into individual pellets, as for instance disclosed in Japanese Patent Publication No. 21421/1973, it is customary to form longitudinal and latitudinal scribed grooves between the respective elements on the wafer by a diamond cutter, and then perform cracking along the respective grooves to thereby obtain semiconductor pellets.
However, according to such a segmentation method, the scribed grooves formed by a diamond cutter are shallow and hence, when cutting out the individual pellets by performing cracking along the scribed grooves, fissures or fractures could be produced in the portions other than the grooves to cause flaws or ruptures in the resultant semiconductor pellets. Also, imperfect segmentation could occur to form two or more unseparated pellets.
For these reasons, the conventional scribing method using a diamond cutter is being superseded by a grinding method using a rotary grinder having at its outer periphery a cutting blade made of diamond grains.
In the grinding method using a rotating grinder blade, grinding work must be carried on while constantly supplying cooling water as well as liquid lubricant to the ground portion and the blade where high heat could otherwise generate during the work. In this case, cuttings such as silicon swarfs driven out along with cooling water migrate on the upper surface of the semiconductor wafer, so that if such cuttings are once deposited on the wafer, it is extremely hard to wash them away in the subsequent cleaning step.